For those of you who remember, I posted a thread a while back asking about two discus shaking their tails at each other. A few days later, one contracted intestinal flagellates. In the process of treating metronidazole, the two started fighting in earnest. In past, the checkerboard bullied the turk - now, probably 'cos of the checkerboard stunting because of flagellates, it has grown just as big, and is reciprocating the aggression. Last time, several members said the two might be pairing up. Jaw locking and whacking each other with their tails isn't a sign of courtship, is it?